摘要:

AbstractCarbonic anhydrase (CA, carbonate hydro‐lyase, EC 4.2.1.1) activity of choroid plexuses (ventricles I + II and IV) and pineal glands of adult male rats was determined by microtitration. Autopsies at precise times in relation to a daily photoperiod 14 hours long allowed in replicate series evaluation of 24‐hour rhythmicity. A slightly lower choroid CA activity during the light phase was variable and marginal in significance. A highly significant and reproducible daily fall in pineal CA activity near the onset of light was paralleled by, and probably originated from, a fall in pineal content of erythrocytes. Low pineal CA activity is consistent with its endocrine nature. Its morning changes in hemodynamics are likely to be due to local changes in content and release of norepinephrine and other vasoactive age

ISSN:0003-276X    

DOI:10.1002/ar.1091740302

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1972

数据来源: WILEY

摘要:

AbstractA quantitative time study of the incorporation of choline‐3H, leucine‐3H and galactose‐3H in lung epithelial cells, was undertakenin vivowith electron microscopic autoradiography. Type II pneumocytes were selectively labeled with choline‐3H, a specific precursor of phosphatidylcholine, which is the main component of pulmonary surfactant. Choline was initially localized in endoplasmic reticulum, then was rapidly transferred through the Golgi complex and stored in lamellar bodies. Previously undescribed small lamellar bodies are suggested as phospholipid carriers between Golgi complex and lamellar bodies. After initial incorporation in the endoplasmic reticulum, the leucine label migrated through the Golgi complex into lamellar bodies by fusion of multivesicular bodies, which are the carriers between the two structures. Galactose was modestly incorporated into lamellar bodies via the Golgi complex. Intra‐alveolar myelin figures, recognized as excreted surfactant, were labeled 120 minutes after injection with the three precursors.These findings indicate that the synthesis of a secretory product by type II pneumocytes involves phospholipid, protein and polysaccharide precursors; the secretory product is segregated as lamellar bodies which are destined to be excreted into the alveolar cavity to become part of the lin

ISSN:0003-276X    

DOI:10.1002/ar.1091740303

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1972

数据来源: WILEY

摘要:

AbstractA scanning electron microscope (SEM) was used to explore the complex surface features of the ampullary structures in the vestibular apparatus of the pigeon. The depth perspective inherent in SEM microscopy enabled: 1. three‐dimensional views of major ampullary structures such as the crista ampullaris, eminentia cruciata, and the planum semilunatum; 2. identification of a tongue‐like structure, the “lingula,” that is part of the eminentia cruciata; 3. the observation that the base of the eminentia is a projection of the crista ampullaris and not a structural partition; and 4. evidence that the lingulae, together with the torus, partition the crista into two separate regions. Additionally, an examination was made of the surface topography of non‐sensory cells in the membranous ampulla.The morphology of the cells and gross ampullary structures observed with SEM are compared to those obtained using light microscopy and where advantageous, complimentary light photomicrographs are

ISSN:0003-276X    

DOI:10.1002/ar.1091740304

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1972

数据来源: WILEY

摘要:

AbstractThe dissolution of the nuclear envelope (NE) has been studied ultrastructurally in mouse oocytes maturingin vitro.NE breakdown begins with the undulation of the nuclear envelope followed by the disappearance of nuclear pores. Subsequently, extensive NE convolutions, possibly caused by impinging microtubules, result in the apposition of adjacent NE segments, the appearance of breaks and the formation of NE doublets. Doublets may also be formed by the apposition of intranuclear cisternae to the inner leaflet of the NE. Nuclear envelope breakdown in mouse oocytes takes approximately three and one‐half hoursin vitro.The fate of the resulting nuclear envelope fragments has been followed in both mouse oocytes and human oogonia. In the mouse, NE doublets separate into individual cisternae, indistinguishable from endoplasmic reticulum, by the time of the first meiotic metaphase. A different fate for NE doublets is suggested in human oogonia which retain NE doublets throughout the division cycle. The nuclear envelope of the daughter cells reforms, at least in part, from NE doublets by separation of the apposed cisternae into single units and the re‐establishment of chromosomal contact. Thus, at least some of the NE appears to be conserved in actively dividing human oogo

ISSN:0003-276X    

DOI:10.1002/ar.1091740305

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1972

数据来源: WILEY

摘要:

AbstractIn two and four‐week old rats three types of follicles were observed: thyroid follicles made of follicular cells and C cells; ultimobranchial follicles (or cysts) and ducts composed of lumen‐bordering cells and subjacent cells; mixed follicles lined by follicular cells on one side and by lumen‐bordering cells on the other. Occasionally C cells were seen in the wall of mixed follicles. On their basal side the lumen‐bordering cells of mixed follicles were in direct contact with the wall of ultimobranchial ducts or cysts. In the wall of these ducts transitional cells were observed. One type had ultrastructural features of subjacent cells (i.e., hemidesmosomes) and of lumen‐bordering cells (i.e., pale cytoplasm and dispersed tonofilaments). Another type of transitional cell had hemidesmosomes and a deeply indented nucleus, like subjacent cells, but had accumulated slightly distended cisternae of rough‐surfaced endoplasmic reticulum and was displaying long slender microvilli, which is typical of follicular cells. A third type of cells were called “young follicular cells.” They contained slightly distended cisternal profiles of rough‐surfaced endoplasmic reticulum collected in one corner of the cells and few apical vesicles. However, their cisternae were less abundant, less distended and had a more restricted distribution than those found in mature follicular cells. Hence the subjacent cells of ultimobran‐chial ducts might possibly give rise to lumen‐bordering cells and to some follicular cells. The latter are associated with the lumen‐bordering cells in the formation of mixed follicles; at the beginning these new follicular cells seem less active than the mature follicular cells. The origin of C cells a

ISSN:0003-276X    

DOI:10.1002/ar.1091740306

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1972

数据来源: WILEY

摘要:

AbstractExamination of the morphology in the submandibular salivary gland, adrenal gland and renal cortex of androgen‐insensitive,tfm/Y mutant mice has revealed predominantly female characteristics. A sexual dimorphism in alkaline‐phosphatase (AP) activity was seen in the submandibular salivary gland of this strain of mice; the AP activity in the mutants was similar to females. There was no dimorphism in renal AP activ

ISSN:0003-276X    

DOI:10.1002/ar.1091740307

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1972

数据来源: WILEY

摘要:

AbstractThe qualitative relationship of dental vascularity to mineralization of dentin and enamel was studied in 50 normal human fetuses 11.5 to 18 weeks of age, obtained unembalmed within 12‐24 hours after abortion. A 50‐50 suspension of India ink and 10% neutral formalin was injected manually into the umbilical vein (intact fetuses) or internal carotid arteries (autopsied fetuses), using sufficient pressure on the syringe to fill but not rupture nor overdistend the blood vessels. After immersion of the injected fetuses in 10% neutral formalin for three to five days, the maxillae and mandibles were removed and stained with alizarin red S for identification of calcium salts. Under magnification the dental sacs were exposed, removed intact and opened to observe: (1) the dental papilla, (2) its size and vascularity, and (3) the extent of mineralization of the crowns and cusps. Macroscopic preparations and microscopic sections were made of selected tissues from these specimens. The degree of mineralization appeared to be correlated more closely with the vascularity of the dental papilla than with the total size of the dental sacs, or that of the cusps or crowns. Blood vessels were present at the peripheral edge of both the developing enamel and dentin but no blood vessels were found to traverse the stellate reticulum nor were any blood cells found within it normally; whereas if abnormal pressure had been applied to the fetus or if the specimens were undergoing maceration, blood cells were observed within the stellate reticu

ISSN:0003-276X    

DOI:10.1002/ar.1091740308

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1972

数据来源: WILEY

摘要:

AbstractUltimobranchial follicles in the thyroid glands of young Wistar rats, 4 to 12 weeks old, are lined by non‐keratinized stratified squamous epithe‐lium and contain desquamated cellular material. Mitoses are observed in the epithelium of these follicles which are variable in size, shape and frequency. Thyroid glands of young vitamin A deficient rats also contain ultimobranchial follicles. These follicles differ from those found in animals on a stock diet in that the stratified squamous epithelium produces keratinized concentric whorls of non‐nucleated luminal debris. After placing vitamin A deficient rats on a stock diet desquamated cellular material is no longer keratinized and resembles that seen in the control animals. Vitamin A deficient diet apparently keratinizes the stratified squamous epithelium of pre‐existing ultimobranchial follicles rather than solely having a metaplastic effect on thyroid‐like follicles of ultimobranchial tiss

ISSN:0003-276X    

DOI:10.1002/ar.1091740309

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1972

数据来源: WILEY

摘要:

AbstractA three dimensional reconstruction of the basal end of the rat incisor, together with analytical data attesting to the reproducibility of the method is presented. The size and shape of the tooth varies little from animal to animal, while the sizes of the functional compartments are much less uniform.The odontogenic sheath is divided into three zones: Proliferation, differentiation and apposition. The proliferative zone is subdivided into two segments: The basal segment which gives rise to ameloblasts shows the highest cell production; an anterior segment located around the pulp opening which will give rise to the part of the tooth covered by cementum and has a much lower cell production.Total cell production can be obtained only in transverse sections, while mid‐sagittal sections can serve only for comparative purpose

ISSN:0003-276X    

DOI:10.1002/ar.1091740310

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1972

数据来源: WILEY

摘要:

AbstractCytoplasmic annulate lamellae are described as occurring in the cells of chick embryo liver during raft‐type organ culture on Eagle's minimum essential medium. These transitory structures, prominent in the cells of early (5‐day) embryonic liver during culture, were closely associated with the outer nuclear membrane and mitochondria, and were frequently continuous with portions of the rough endoplasmic reticulum. In contrast, annulate lamellae were not found in any cell examined during organ culture of older (11‐day) embryonic liver. These observations, together with correlative enzymatic studies, are discussed with regard to the possible role of annulate lamellae in the differentiation of the liver cell, in the light of current hypotheses on the origin and function of these widely‐occurring org

ISSN:0003-276X    

DOI:10.1002/ar.1091740311

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1972

数据来源: WILEY